Re: [Qemu-devel] [PATCH] cpu: smp_wmb before lauching cpus.

[Jan Kiszka]

On 2012-07-05 13:02, liu ping fan wrote:
> On Thu, Jul 5, 2012 at 6:16 PM, Jan Kiszka <address@hidden> wrote:
>> On 2012-07-05 12:10, liu ping fan wrote:
>>> On Thu, Jul 5, 2012 at 2:46 PM, Jan Kiszka <address@hidden> wrote:
>>>> On 2012-07-05 04:18, Liu Ping Fan wrote:
>>>>> Vcpu state must be set completely before receiving INIT-IPI,SIPI
>>>>>
>>>>> Signed-off-by: Liu Ping Fan <address@hidden>
>>>>> ---
>>>>>  kvm.h |    1 +
>>>>>  1 files changed, 1 insertions(+), 0 deletions(-)
>>>>>
>>>>> diff --git a/kvm.h b/kvm.h
>>>>> index 9c7b0ea..5b3c228 100644
>>>>> --- a/kvm.h
>>>>> +++ b/kvm.h
>>>>> @@ -198,6 +198,7 @@ static inline void 
>>>>> cpu_synchronize_post_init(CPUArchState *env)
>>>>>  {
>>>>>      if (kvm_enabled()) {
>>>>>          kvm_cpu_synchronize_post_init(env);
>>>>> +        smp_wmb();
>>>>>      }
>>>>>  }
>>>>>
>>>>>
>>>>
>>>> In theory, there should be no vcpu kick-off after this without some
>>>> locking operations involved that imply barriers. Did you see real
>>>
>>> Yeah, but what if it is non-x86?
>>
>> The locking I'm referring to is arch independent.
>>
>>>> inconsistencies without this explicit one?
>>
>> Again: Did you see real issues or is this based on static analysis?
>>
> Just on  static analysis

Then please describe - also for the changelog - at least one case in
details where this is needed.

Thanks,
Jan

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